High Pressure Wireline Top-Entry Packoff Apparatus and Method

ABSTRACT

A high-pressure packoff apparatus and method are disclosed. The packoff allows wireline entering a top drive drilling head through a top entry access system to be isolated in such a fashion to minimize the leakage and escape of drillstring fluids to the atmosphere. Optionally, an extension housing containing a flow tube assembly can be employed to accomplish the task. The flow tube assembly effectuates a pressure drop along the wireline conduit run therethrough, thus minimizing the likelihood of fluid escaping.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present invention claims the benefit of U.S. Provisional ApplicationSer. No. 60/481,659 filed Nov. 18, 2003 by Vernon Kauffman and DwightLeBlanc, entitled “High Pressure Wireline Top-Entry Packoff Apparatusand Method,” hereby incorporated by reference herein.

BACKGROUND OF THE INVENTION

The present invention relates to an apparatus for use on a drilling rig;specifically to a high-pressure wireline packoff seal apparatus for useon top-drive drilling rigs and the methods of using the same.

The majority of large oil well drilling rigs operating throughout theworld now use top-drive units to speed the assembly of drill string andto permit rapid, almost continuous, drilling. Wireline operationsrequired on deep wells using these expensive rigs can be a severebottleneck if they cannot be carried out with the expediency andefficiency sought by all drilling contractors. To remedy the problem ofinserting a wireline through a top-drive unit, a top-entry apparatusproviding a safe and effective means of inserting and manipulating awireline in a top-drive unit has been developed. Top entry systems offeroilfield companies the opportunity to perform certain types of wirelineoperations under elevated drilistring bore and annulus pressures. Suchwireline operations include, but are not limited to, pipe recovery,backoff, formation evaluation, and directional drilling operations.Because of the various requirements and measurements recorded duringsome of these wireline operations, it is often necessary to maintainthis elevated pressure before, during, and after their commencement.

There presently exists an important and long-felt need for a hydraulicpackoff system and method with a top drive, top entry, wirelineoperations scheme that will allow operations to continue withoutreducing drilistring pressures. In order to accomplish this, a highquality seal mechanism is desired. Such a seal would enable the wirelineto communicate with the drillstring bore while allowing the escape orleakage of only minimal amounts of bore fluids. The various embodimentsof the present invention all address this particular need.

BRIEF SUMMARY OF THE INVENTION

The deficiencies of the prior art are addressed by a top entry accesssystem including a hydraulic packoff to allow a conduit into a bore of adrillstring. The hydraulic packoff preferably includes a main bodywherein the main body preferably has a lower connection, a seal bore, anupper connection, and a mounting surface. The lower connection ispreferably configured to attach to an inlet of the drilistring and theseal bore is preferably configured to receive a gland assembly.Preferably, the seal gland assembly is configured to allow the conduitto communicate with the bore of the drillstring without releasingdrilling fluids therefrom. Preferably, the mounting surface of the mainbody is configured to receive and secure the top entry access systemthereupon.

The deficiencies are also addressed by a hydraulic packoff for a topdrilling assembly wherein the packoff includes a main body having alower connection, a seal bore, and a roller assembly. Preferably theseal bore is configured to receive a seal gland assembly with the sealgland configured to allow a conduit to communicate with a bore of adrillstring without releasing drilling fluids therefrom. Preferably, theroller assembly is positioned above and configured to guide the conduitinto the gland assembly.

The deficiencies can also be addressed by a hydraulic packoff for a topdrilling assembly wherein the packoff includes a main body having alower connection, a seal bore, and a retaining nut. Preferably the sealbore is configured to receive a seal gland assembly with the seal glandconfigured to allow a conduit to communicate with a bore of adrillstring without releasing drilling fluids therefrom. Preferably, theretaining nut is configured to compress the gland assembly.

The deficiencies are further addressed by a method for entering aconduit into a drillstring driven by a top drive assembly wherein themethod preferably comprises connecting a hydraulic packoff and anextension housing to a drillstring inlet above the top drive assembly.Preferably, the method also includes installing a flow tube assemblyinside a bore of the extension housing and connecting a top entry accesssystem above the hydraulic packoff. The method includes routing theconduit from a supply, through the top entry access system, into thehydraulic packoff, through the hydraulic packoff, through the flow tubeassembly, through the drillstring inlet and into the drillstring.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more detailed description of the preferred embodiments of thepresent invention, reference will not be made to the accompanyingdrawings, wherein:

FIG. 1A is a sectioned profile view drawing of a wireline packoffapparatus in accordance with the present invention installed inconjunction with a top entry access system.

FIG. 1B is a sectioned side view drawing of the wireline packoffapparatus shown in FIG. 1A.

FIG. 2 is a sectioned view drawing of a wireline packoff apparatus inaccordance with the present invention installed in conjunction with analternate top entry access system.

FIG. 3 is a cross-sectional drawing of a wireline packoff apparatus inaccordance with a first preferred embodiment of the present invention.

FIG. 4 is a cross-sectional drawing of a wireline packoff apparatus inaccordance with a second preferred embodiment of the present invention.

FIG. 5 is a cross-sectional drawing of a wireline packoff apparatus inaccordance with a third preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring initially to FIGS. 1A-1B, a high-pressure packoff 10 enables awireline conduit 20 to enter a bore of a drillstring (not shown) from atop entry access system 12 above an oilfield top-drive assembly (notshown). While conduit 20 is preferably constructed as a high tensilestrength jacketed electrical conductor, it should be understood by oneof ordinary skill in the art that any flexible oilfield communicationconduit can be used with the various embodiments of the presentinvention. Examples of such conduits can include, but are not limitedto, single or multiple electrical conductor wireline, fiber optic cable,braided steel cable, coiled tubing, and slickline.

Top entry access system 12 typically includes a pair of large diametersheave wheels 16, 17 between two plates 18, 19 but can be of any otherconfiguration known to one skilled in the art. For example, referringbriefly to FIG. 2, an alternative top entry access system 12A is shown.Alternative access system 12A includes a single large diameter sheavewheel 16A at its top but instead of a lower sheave wheel, has aplurality of small-diameter rollers 22 to guide conduit 20 intolocation. Furthermore, alternative access system 12A also includes astructural support bar 24 to rigidly secure system 12A to lifting bales26 and to prevent flexure. For examples of top entry access andtop-drive systems entry, see U.S. Pat. No. 5,735,351 entitled “Top EntryApparatus and Method for a Drilling Assembly” issued to Charles M. Helmson Apr. 7, 1998 and U.S. patent application Ser. No. 10/249,033 entitled“Universal Top-Drive Wireline Entry System Bracket and Method” filed onMar. 11, 2003 by Kauffman, et al, both hereby incorporated herein byreference.

Returning again to FIGS. 1A-1B, packoff 10 is preferably situatedbetween entry access system 12 and a manifold 14 located above the topdrive assembly. Manifold 14 preferably includes a first inlet 28 toallow the entry of conduit 20 into the drillstring bore, and a secondinlet 30 to allow the entry and pressurization of fluids into thedrillstring bore. Manifold 14 is shown with a threaded connector 32 toallow attachment to the top drive assembly. Packoff 10 is preferablyconstructed to isolate the pressurized bore of drillstring from theatmosphere while still allowing the insertion and removal of conduit 20in and out thereof. Furthermore, packoff 10 is preferably constructed toallow rotational movement of top entry access system with respect tomanifold 14 and top drive assembly without compromising the sealingmechanism of packoff 10. Finally, packoff 10 is preferably constructedas a robust device, one that will not fail under bending and torsionalloading from top entry access system 12 through manipulation of conduit20.

Referring now to FIG. 3, a packoff 50 assembly in accordance with afirst preferred embodiment of the present invention is shown in moredetail. Packoff assembly 50 is shown having a main body 52, a glandassembly 54, and a roller assembly 56. Main body 52 preferably includesan outer journal surface 58, a thrust surface 60, an internal seal bore62, a bottom threaded connection 64, and an upper threaded connection66. Surfaces 58, 60 are preferably provided to receive the connectingtop entry access system that is mounted thereupon and provide a journalsurface for rotational movement thereof of and a thrust surface foraxial loads therefrom. Depending on configuration, Journal surface 58can be constructed either to allow rotation of access system 12 or notto allow such rotation. In circumstances where free movement of accesssystem 12 is desired, journal surface 58 can be constructed as a journalbearing surface, one that would allow such movement. In othercircumstances where the movement of access system 12 is preferred to berestricted, an ordinary journal surface 58 can be employed.Alternatively, Top entry access system can connect to other rigsitestructures such as lifting bales or the top drive head itself. Internalseal bore 62 houses packoff gland assembly 54 that includes a bladder68, a split rubber 70, and a line rubber 72. Backup rings 74 arepositioned at the top and bottom of bladder 68 and include o-ring seals76. Backup rings 74 and seals 76 help seal, isolate, and compressbladder 68, and rubbers 70, 72 against wireline (20 of FIGS. 1-2) runtherethrough.

At its bottom, packoff gland assembly 54 is held in place by a bottomplate 78 secured by a bottom lip 80 of main body 52. Optionally, belowbottom lip 80 of main body 52, a pin insert 82 and sealing ring 90 canbe installed with bolts 84 to help align packoff assembly 50 intoposition on top of top drive assembly. At its top, packoff glandassembly 54 is compressed and held into place with an upper retainer nut86. Upper retainer nut 86 has an outer threaded profile 88, and an innerthreaded profile 90. Retainer nut 86 is installed by threading outerprofile 88 into thread profile 66 of main body 52 until gland assembly54 is properly compressed. Once retainer nut 86 is in position, apackoff safety cap 94 is installed and secured with bolts 96.

Above main body 52 roller assembly 56 is optionally installed. Rollerassembly 56 preferably includes roller body 98, a plurality of rollers100, a bushing 102, and a bushing cage 104. Rollers 100, mounted at thetop of roller body 98 and secured with bearing pins 106 and cotter keys108, smoothly guide wireline 20 into the main body 52 and through thegland assembly 54. A threaded profile 110 is located at the bottom ofroller body 98 and corresponds with internal threaded profile 90 toengage roller assembly 56 into upper retainer nut 86. Bushing 102,preferably constructed of brass or any other standard bushing material,acts in conjunction with bushing cage 104 to compress and hold linerubber 72 in place.

Wireline conduit 20 enters packoff assembly 50 of FIG. 3 at rollers 100,travels through bushing 102 to line rubber 72 and out through bottomplate 78 and pin insert 82 and into top drive drilling head assembly. Alubrication channel 112 is preferably pressurized with lubrication oilor other suitable lubricating fluid to help maintain the sealing ofwireline 20. Seals 77, 90, and bladder 68 maintain the isolation oflubrication channel 112 from the atmosphere.

Referring now to FIG. 4, a packoff assembly 120 in accordance with asecond preferred embodiment of the present invention is shown. Packoffassembly 120 is shown similarly to packoff assembly 50 of FIG. 3, butwith the inclusion of an extension housing 122 and a flow tube assembly124. As with assembly 50 of FIG. 3, packoff assembly 120 includes a mainbody 126 and a gland assembly 128. Main body 126 includes upper andlower threaded profiles 130, 132, an outer bearing surface 134, and abore 136 to receive gland assembly 128. Gland assembly 128 is held inplace with a gland retainer nut 138 but a seal retainer 140 holds glandassembly 128 in compression rather then a bushing and roller assembly(102 and 56 of FIG. 3). Extension housing 122 includes an upper threadedprofile 142, a lower mating pin 144, a receptacle bore 146, and athreaded securing nut 148. Extension housing 122 is installed upon thewireline entry inlet 28 of manifold 14, located just above the top driveassembly (not shown). While one embodiment of extension housing 122 isshown, it should be understood by one of ordinary skill in the art thathousing 122 can be constructed in many different manners withoutdeparting from the spirit of the invention. Particularly, extensionhousing can be constructed integral to main body 52 of packoff assembly50 (or 120), while maintaining the same characteristics of housing 122shown in FIGS. 4 and 5.

Extension housing 122 allows for the installation of flow tube assembly124 to help reduce the bore fluid pressure acting on wireline conduit 20as it exits gland assembly. Flow tube assembly 124 includes a pluralityof expansion cavities 150 that extend around wireline 120 from thebottom to the top of flow tube 124. A fluid port 152 is connected to amain cavity 154 of flow tube 124 and is used to remove pressurized borefluids from around wireline 20. Because of elevated borehole pressures,flow tube assembly 124 needs to be held in place inside housing 122 witha nut or a c-ring (not shown). Otherwise, sudden elevations in borepressure could cause flow tube assembly 124 to “blow out” of its seat inhousing 122.

As pressurized fluids flow from bottom of flow tube 124 to main cavity154 the pressure is incrementally dropped after experiencing each cavity150. Finally, fluids are siphoned off at port 152 to further effectuatethe pressure drop, resulting in a fluid pressure at gland assembly 128that is significantly lower than the fluid pressure at the top drivedrilling assembly. This reduced pressure at gland assembly 128, allowsfor the insertion and removal of wireline conduit 20 from the drillingassembly with little or no escaping bore fluids. While a particularconstruction for flow tube assembly 124 is shown, it should beunderstood that various designs can be created and used by one skilledin the art. For instance, a flow tube with varying profiles and numbersof expansion cavities 150 can be used. The specific design andconstruction of flow tube assembly 124 will depend on variables such asbore pressure, the size of conduit 20, and the amount and rate ofpressure drop desired. The example shown is not meant to limit thedesign, configuration, and construction of flow tube assembly 124, butis merely illustrative.

Referring still to FIG. 4, one method of installing packoff assembly 120with flow tube assembly 124 can be described. Extension housing 122 canfirst be installed atop entry inlet 28 of manifold 14 placing mating pin144 into inlet 28 and tightening securing nut 148. Securing nut 148 hasinternal threads 156 that correspond to mating outside threads 158 ofinlet 28. Furthermore, an o-ring 160 is positioned on the outside ofmating pin 144 to prevent the leakage of fluids therefrom. WithExtension housing 122 secured to manifold 14, flow tube assembly 124 canthen be inserted into the receptacle bore 146 of extension housing 144.O-rings 162 on the outer surface of flow tube assembly 124 arelubricated and installed to prevent the fluids from bypassing theinternal cavities 150, 154 of flow tube assembly 124.

Next, a length of wireline conduit 20 is released and fed through thegland assembly 128 and main body 126 and then fed through flow tubeassembly 124. With wireline conduit 20 pre-fed, main body 126 isthreaded onto the upper threads 142 of extension housing 122 withcorresponding lower thread profile 132. When packoff assembly 120 is soassembled, Top entry access system 12 can then be secured to the outerbearing surface 134 of main body 126. Preferably, upper threads 142 ofextension housing 122 and mating outside threads 158 of inlet 28 are ofthe same design and construction. This way, if the flow tube assembly124 is not needed for a particular operation, main body 126 can bethreaded directly onto pin 28 without installing extension housing 122,similar to assembly shown in FIGS. 1-3.

Referring briefly to FIG. 5, a packoff assembly 220 in accordance with athird preferred embodiment of the present invention is shown. Packoffassembly 220 similar to packoff assembly 120 of FIG. 4, but with theaddition of a roller body 298 to the top of main body 226. Roller body298 acts in a manner similar to roller body 98 of FIG. 3 and helps guidewireline conduit 20 from top entry access system 12 into main body 226,through flow tube assembly 224 and extension housing 222 and into entryinlet 28 of manifold 14. As with extension housing 122 of FIG. 4,extension housing 222 is secured atop inlet 28 with a securing nut 248that engages outer threads 258 of pin. Roller body 298 of FIG. 5 wouldbe installed atop gland assembly (not shown in FIG. 5) in place of theretainer nut 138 shown in FIG. 4. Alternatively, roller body 298 couldbe secured to the top of retainer nut 138 by any means known by one ofordinary skill in the art.

Numerous embodiments and alternatives thereof have been disclosed. Whilethe above disclosure includes the best mode belief in carrying out theinvention as contemplated by the named inventors, not all possiblealternatives have been disclosed. For that reason, the scope andlimitation of the present invention is not to be restricted to the abovedisclosure, but is instead to be defined and construed by the appendedclaims.

1. A top drive entry access system including a hydraulic packoff toallow a conduit into a bore of a drillstring, the hydraulic packoffcomprising: a main body, said main body having a lower connection, aseal bore, an upper connection configured to receive a roller assemblyto guide the conduit from the top drive entry access system into a glandassembly, wherein said roller assembly includes a bushing to compresssaid gland assembly, and a mounting surface; said lower connectionconfigured to attach to an inlet of the drillstring; said seal boreconfigured to receive said gland assembly; said gland assemblyconfigured to allow the conduit to communicate with the bore of thedrillstring without releasing drilling fluids therefrom; and saidmounting surface configured to receive and secure the top drive entryaccess system thereupon, wherein said mounting surface includes ajournal bearing surface configured to allow the rotational movement ofthe top drive entry access system with respect to said main body. 2-9.(canceled)
 10. The top drive entry access system of claim 1 wherein saidinlet is positioned on a manifold above a top drive drilling head. 11.The top drive entry access system of claim 1 wherein an extensionhousing and a flow tube assembly are positioned between said inlet andsaid main body.
 12. The top drive entry access system of claim 11wherein said extension housing is integral to said main body.
 13. Thetop drive entry access system of claim 11 wherein pressures of saiddrilling fluids are reduced as said fluids extend up said flow tubeassembly along the conduit.
 14. The top drive entry access system ofclaim 1 further comprising a flow tube assembly including a through boreand a plurality of expansion cavities arrayed along a length of saidthrough bore; said through bore configured to receive the conduittherethrough; said through bore in fluid communication with saidexpansion cavities; and said expansion cavities configured to create apressure reduction profile about the conduit as it extends along saidlength of said through bore.
 15. The top drive entry access system ofclaim 14 wherein said flow tube assembly includes a fluid portconfigured to remove fluids and pressure from said through bore.
 16. Ahydraulic packoff for a top drive entry drilling assembly, the hydraulicpackoff comprising: a main body, said main body having a lowerconnection, a seal bore, and a roller assembly; said seal boreconfigured to receive a seal gland assembly configured to allow aconduit to communicate with a bore of a drillstring without releasingdrilling fluids therefrom; and said roller assembly positioned above andconfigured to guide said conduit into said seal gland assembly, whereinsaid roller assembly includes a bushing to compress said seal glandassembly. 17-20. (canceled)
 21. The hydraulic packoff of claim 16further comprising a mounting surface to attach a top drive entry accesssystem.
 22. The hydraulic packoff of claim 21 wherein said mountingsurface includes a journal bearing configured to allow the rotationalmovement of said top drive entry access system with respect to said mainbody.
 23. The hydraulic packoff of claim 21 wherein said mountingsurface includes a thrust bearing configured to resist thrust andbending forces exerted by said top drive entry access system on saidmain body.
 24. The hydraulic packoff of claim 16 wherein said lowerconnection connects to an entry inlet of the top drive drillingassembly.
 25. The hydraulic packoff of claim 16 further comprising anextension housing extending from said lower connection, said extensionhousing providing a seal bore to receive a flow tube assembly.
 26. Thehydraulic packoff of claim 16 further comprising: a flow tube assembly,said flow tube assembly comprising a through bore and a plurality ofexpansion cavities arrayed along a length of said through bore; saidthrough bore configured to receive the conduit therethrough; saidthrough bore in fluid communication with said expansion cavities; andsaid expansion cavities configured to create a pressure reductionprofile about the conduit as it extends along said length of saidthrough bore.
 27. The hydraulic packoff of claim 26 wherein said flowtube assembly includes a fluid port configured to remove fluids andpressure from said through bore. 28-32. (canceled)
 33. A hydraulicpackoff for a top entry drilling assembly, the hydraulic packoffcomprising: a main body, said main body having a lower connection, aseal bore, and a retaining device; a seal gland configured to bereceived in said seal bore, said seal gland configured to allow aconduit to communicate with a bore of a drillstring without releasingdrilling fluids therefrom; a flow tube assembly, said flow tube assemblycomprising a through bore and a plurality of expansion cavities arrayedalong a length of said through bore; said through bore configured toreceive the conduit therethrough; said through bore in fluidcommunication with said expansion cavities; said expansion cavitiesconfigured to create a pressure reduction profile about the conduit asit extends along said length of said through bore; and said retainingdevice positioned above and configured to compress said gland assembly.34. The hydraulic packoff of claim 33 wherein said retaining device is aroller head.
 35. The hydraulic packoff of claim 34 wherein saidretaining device is a retaining nut.
 36. A method for entering a conduitinto a pressurized bore of a drillstring driven by a top drive assembly,the method comprising: connecting a hydraulic packoff and an extensionhousing to an inlet of the drillstring, the inlet located above a drivemotor of the top drive assembly; installing a flow tube assembly insidea bore of the extension housing; connecting a top entry access systemabove the hydraulic packoff; and routing the conduit from a supply,through the top entry access system, into the hydraulic packoff, throughthe flow tube assembly, through the drillstring inlet and into thedrillstring. 37-38. (canceled)
 39. The method of claim 36 furthercomprising removing pressurized fluid from a fluid port in communicationwith a through bore of said hydraulic packoff assembly on the top driveassembly to reduce the pressure in the through bore and in the hydraulicpackoff. 40-42. (canceled)